04:19 duration 4 minutes 19 seconds
Vera Rubin and Dark Matter
Excerpts from The Ring of Truth, Episode 6: Doubt, hosted by Philip Morrison https://www.youtube.com/watch?v=xhfUfxeh9Lg
34:38 duration 34 minutes 38 seconds
HYD151: Velocity Measurement, part 2
This 35-minute presentation explains the various technologies available to measure velocity in a river.